|
From: | Alberto Garcia |
Subject: | Re: [Qemu-devel] [PATCH v12 09/10] qcow2: skip writing zero buffers to empty COW areas |
Date: | Tue, 15 Jan 2019 16:27:59 +0100 |
User-agent: | Notmuch/0.18.2 (http://notmuchmail.org) Emacs/24.4.1 (i586-pc-linux-gnu) |
On Mon 14 Jan 2019 12:18:30 PM CET, Anton Nefedov wrote: > If COW areas of the newly allocated clusters are zeroes on the backing image, > efficient bdrv_write_zeroes(flags=BDRV_REQ_ALLOCATE) can be used on the whole > cluster instead of writing explicit zero buffers later in perform_cow(). > > iotest 060: > write to the discarded cluster does not trigger COW anymore. > Use a backing image instead. > > Signed-off-by: Anton Nefedov <address@hidden> > Reviewed-by: Vladimir Sementsov-Ogievskiy <address@hidden> Reviewed-by: Alberto Garcia <address@hidden> > + ret = handle_alloc_space(bs, l2meta); I insist that it would be nice to have a short comment explaining what this does. Berto
[Prev in Thread] | Current Thread | [Next in Thread] |